wiktionary.org provides an API for example:
http://en.wikipedia.org/w/api.php?action=query&list=search&srsearch=Television&format=json
gives back
    {
       "query": {"searchinfo": {"totalhits": 208862},
       "search": [{ 
           "ns": 0, 
           "title": "Television", 
           "snippet": "<span class='searchmatch'>Television<\/span> (TV) is a widely used telecommunication  medium  for transmitting and receiving moving images , either monochromatic  (\"black  <b>...<\/b> ",
           "size": 28228, 
           "wordcount": 3566, 
           "timestamp": "2009-10-02T15:09:56Z"},
...
       ]},
       "query-continue": {"search": {"sroffset":10}}
    }